Molecular Adjuvant Ag85A Enhances Protection against Influenza A Virus in Mice Following DNA Vaccination

Mingyuan Li,Baoning Wang,Huan Wang,Laifeng Ren,Jingjing Shao,Jun Dai,Sha Li,Decui Pei,Bin Zuo,Yu Kuang,Kang Cao,Hong Li

doi:10.3390/v4123606

Abstract

A novel DNA vaccine vector encoding the Mycobacterium tuberculosis secreted antigen Ag85A fused with the influenza A virus (IAV) HA2 protein epitopes, pEGFP/Ag85A-sHA2 (pAg85A-sHA2), was designed to provide protection against influenza. The antigen encoded by the DNA vaccine vector was efficiently expressed in mammalian cells, as determined by reverse transcription polymerase chain reaction (RT-PCR) and fluorescence analyses. Mice were immunized with the vaccine vector by intramuscular injection before challenge with A/Puerto Rico/8/34 virus (PR8 virus). Sera and the splenocyte culture IFN-γ levels were significantly higher in immunized mice compared with the control mice. The novel vaccine group showed a high neutralization antibody titer in vitro. The novel vaccine vector also reduced the viral loads, increased the survival rates in mice after the PR8 virus challenge and reduced the alveolar inflammatory cell numbers. Sera IL-4 concentrations were significantly increased in mice immunized with the novel vaccine vector on Day 12 after challenge with the PR8 virus. These results demonstrated that short HA2 (sHA2) protein epitopes may provide protection against the PR8 virus and that Ag85A could strengthen the immune response to HA2 epitopes, thus, Ag85A may be developed as a new adjuvant for influenza vaccines.

Highlights

The influenza A virus (IAV) pandemic of 2009 involving the H1N1 strain has raised international concern over the potential for outbreaks of increased severity and highlighted the need for improved global surveillance and vaccination strategies [1,2]
These results indicated that the HA, Ag85A, short HA2 (sHA2) and the Ag85A-sHA2 fusion genes could be transiently expressed in HEK293 cells
HEK293 cells. (A) Expression was evaluated by reverse transcription polymerase chain reaction (RT-PCR) as follows: (1) cells transfected with pHA; (2) cells transfected with pAg85A-sHA2; (3) cells transfected with pAg85A; (4) cells transfected with psHA2; (5)–(8) cells transfected with pEGFP-C2; (M) Trans2K Plus DNA Marker

Summary

Introduction

The influenza A virus (IAV) pandemic of 2009 involving the H1N1 strain has raised international concern over the potential for outbreaks of increased severity and highlighted the need for improved global surveillance and vaccination strategies [1,2]. It is of substantial interest to develop a vaccine that targets conserved viral proteins (e.g., M2e, NP) and could be used to protect against unpredicted antigenic variation in both epidemic and pandemic outbreaks. These conserved viral protein vaccines do not usually target the surface molecules of IAV. This has resulted in a substantial drop in the efficacy of vaccination. It is important to develop a vaccine that targets the surface molecule of IAV

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